The Brazilian Portuguese version of the Pregnancy Mobility Index: Cross-cultural adaptation and psychometric evaluation – a validation study

ABSTRACT BACKGROUND: The Pregnancy Mobility Index (PMI) was developed to assess mobility in pregnant women in the Netherlands. At present, no similar questionnaire is available in Brazil. OBJECTIVE: The present study aimed to translate, cross-culturally adapt, and evaluate the psychometric properties of a Brazilian PMI. DESIGN AND SETTING: The present study was a validation study conducted at the Universidade Federal do Paraná and a public maternity ward in Curitiba, Brazil. METHODS: Text translation and cross-cultural adaptation followed international guidelines. Construct validity, internal consistency, and inter- and intra-rater reliability tests included 97 women. The Pelvic Girdle Questionnaire, Multidimensional Pain Evaluation Scale, Schober’s test, and lumbar spine range of motion assessment were administered on the first day. Intra-rater reliability (n = 19) was measured after 15 days. Exploratory factor analysis was performed, and the correlation matrix was analyzed using Pearson’s coefficient. RESULTS: Pregnant women (88%) understood the cultural adaptation process. The internal consistency was high (Cronbach’s alpha > 0.90), construct validity was moderate, with significant correlation between lumbar spine range of motion (r = 0.283–0.369) and Schober’s test (r = -0.314), and high correlation between the Multidimensional Pain Evaluation Scale (r = -0.650 and -0.499) and Pelvic Girdle Questionnaire (r = -0.737). Intra- and inter-rater reliabilities were excellent (intraclass correlation coefficient = 0.932 and 0.990, respectively). CONCLUSION: The Brazilian version of the PMI was successfully translated with excellent reliability and moderate-to-high construct validity. It is an important tool for assessing mobility in pregnant women. CLINICAL TRIAL: RBR-789tps (Validation study), https://ensaiosclinicos.gov.br/rg/RBR-789tps.


INTRODUCTION
The anatomical and physiological changes that occur during pregnancy frequently increase musculoskeletal disorders. Symptoms frequently related to pregnancy are largely due to ligamentous laxity and joint hypermobility, which are associated with hormonal changes and weight gain.
This, in turn, increases mechanical stress. Additionally, pregnant women have a displaced center of gravity, which is associated with hyperlordosis that contributes to the mechanical strain on the sacroiliac and back joints. 1,2 Low back and pelvic girdle pain are the most frequent complaints during pregnancy, and both negatively affect mobility and functionality, contributing to physical disability that can affect work performance and day-to-day activities. 3,4 Although there are several questionnaires that evaluate disability and loss of mobility caused by back pain in the general population, none are specific to pregnant individuals. 3,4 Pregnancyrelated back pain differs from that in the general population, and has distinctive mobility patterns and expectations. 4 A questionnaire is a tool that transforms subjective information into objective and measurable data. In this way, it is possible to demonstrate the patient's evolution to them in a clearer and more understandable way. The advantage of using questionnaires is that they are self-reported by the patient or the healthcare worker, in research or the clinical setting. In clinical practice, questionnaires can become a facilitator for medical records, assisting the healthcare professional in understanding the patient's needs and, later, in the execution of the treatment plan. 5 In Brazil, there is only one questionnaire available with which to assess the interference of lumbopelvic pain in sexual activity, sleep quality, and day-to-day activities during pregnancy. 3 As of yet, there is no questionnaire that assesses the mobility of pregnant women which has been validated for the Brazilian population; 3,4 however, the Pregnancy Mobility Index (PMI) could fill this gap, as it was developed to specifically assess this variable. 4 The PMI, composed of 24 questions which aim to assess the effects of low back and pelvic pain during and after pregnancy on day-today activities, is considered a reliable and valid instrument when applied to the Dutch population. The PMI can also assess the effects of pain interventions and help understand normal levels of mobility during pregnancy. 4

OBJECTIVE
The aim of the present study was to provide a cross-cultural adaptation and psychometric evaluation of a Brazilian Portuguese version of the PMI.

METHODS
The present validation study, performed using the Consensus- Ward, and at the Prevention and Rehabilitation in Physical Therapy Department of the UFPR. All individuals provided written informed consent prior to participating in the study.
To begin, we requested authorization for the translation and validation of a Brazilian Portuguese version of the PMI. The Dutch and English versions of the PMI were utilized for the preparation of the Brazilian version. 4,7 The process of translation, back translation, and cross-cultural adaptation rigorously followed the Guidelines for the Process of Cross-Cultural Adaptation of Self-Report Measures. 8 Four bilingual translators, all native speakers of Brazilian Portuguese, translated the instrument; two were healthcare professionals (T1D and T1E), while the other two had no healthcare experience (T2D and T2E). The translations were discussed by the translators and the authors of the present study, and the first version of the translated PMI was created (T-12D and T-12E). This version was translated back to English and Dutch by four native speakers, none of whom were healthcare professionals or had prior knowledge of the original version of the PMI (BT1D, BT2D, BT1E, and BT2E). To reach a consensus, a committee of experts reviewed a document containing the translations, back-translations, original versions, and a report prepared by the research team, including each item of the instrument, alternative answers, and instructions. The committee's decisions were aimed at ensuring semantic, idiomatic, experimental, and conceptual equivalence between the versions. The pre-final version was administered to 30 eligible participants to evaluate for any difficulties in item comprehension.
In order to verify the comprehension of the instrument by the participants, we followed the steps described in a previous study. 9 Pregnant women were questioned about the comprehension of each item, and answers were based on a scale that ranged from as an answer (this item, when checked, was not used to calculate the final score).
After the translation and cross-cultural adaptation, validity and reliability were assessed at a public maternity hospital. Primiparous and multiparous pregnant women at a gestational age > 20 weeks, without cognitive deficits, and who were native Brazilian Portuguese readers were included. Women were excluded if they had a highrisk pregnancy (twins, triplets, or more pregnancies and/or with diabetes, hypertension, measles, rubella, and/or a urinary tract infection), had psychiatric and/or neurological disorders, and/or were unable to perform the tests.
Sociodemographic data were collected during the first interview, The participants were asked to answer the Brazilian Portuguese PMI multiple times -first at the beginning of the interview (Examiner 1) and again after 30 minutes (Examiner 2). In the same interview, lumbopelvic incapacity was evaluated using the Pelvic Girdle Questionnaire (PGQ), 11 pain intensity was evaluated using the Multidimensional Pain Evaluation Scale, 12 and lumbar spine range of motion was evaluated using the modified Schober's test 13 and fleximetry. 14 In the second interview, which was arranged on average 15 days after the first interview, the PMI was completed again, by 19 pregnant women who had already answered the PMI at the first assessment, via a posting by Examiner 1 on a mobile instant messaging service. The participants did not receive any interventions or treatment for low back or pelvic pain during the study period.
In the present study, we made changes in the following: 1) the way the questions were described (statement); 2) we added an answer option ("not applicable") to the questions; and 3) we added a scoring formula to the questionnaire, which guarantees a consistent calculation of the final score. Semantic and cultural adaptations provided the greatest comprehension of the questionnaire.
The final score was calculated by adding the score obtained for each question, multiplying by 100, and dividing by the number of questions scored multiplied by 3. The final scores ranged from 0-100, where 0 equaled 'normal performance' and 100 indicated 'maximum disability' , and consisted of the mobility index of the pregnant woman, as formulated below.

Statistical analysis
Descriptive statistics (mean and standard deviation for continuous data, and frequency and percentages for categorical data) were analyzed to characterize the participants. All analyses were performed using a 95% confidence interval (CI). The intraclass correlation coefficient (ICC) and Bland-Altman method 15,16 were utilized to evaluate the inter-and intra-rater reliability and concordance of the PMI, respectively. ICCs were interpreted as follows: poor (< 0.4); fair (0.4-< 0.6); good (0.6-< 0.75); and excellent (≥ 0.75). 15 The factor analysis followed the main component The sample size was determined according to guidance from Terwee et al., 18 which suggested a ratio of ≥ 4-10 participants for each instrument containing 24 questions. A total of 106 pregnant women participated in the present study, although 9 were excluded because they were either high-risk (n = 6) or failed to complete the proposed tests (n = 3). The final validation sample included a total of 97 pregnant women. The validation phase included a total of 97 pregnant women.

Some
The mean age was 26.8 ± 6.2 years, and the intensity of the low back pain was considered light before pregnancy and advancedto-moderate during pregnancy. The results are shown in Table 1.
The reliability and concordance results of the intra-and interrater reliability tests, which are shown in Table 2, indicated high intra-and inter-rater reliability (ICC = 0.93 and 0.99, respectively).
The paired-samples Student's t-test did not show significant differences in the average test-retest scores for intra-examiner reliability (P = 0.722), although it was different (P = 0.000) from interexaminer reliability. Bland-Altman plots (Figures 1A-B), however,  Table 4.

DISCUSSION
The main findings of the present study are related to the translation and cross-cultural adaptation of the Brazilian Portuguese version of the PMI. The results of the present study indicate that the Brazilian Portuguese PMI is reliable, consistent, and can discriminate between regular and irregular mobility.
The translation, validity, and reliability process should be rigorously followed, as the assessment tools must be precise, objective, and of high quality. 8,18 The present study carefully followed guidelines specifying how to perform a psychometric evaluation of a questionnaire, 19 based on suggestions regarding the use of guidelines for the cross-cultural adaptation of patient-reported outcome measurements. 8 Other studies reinforce the importance of ensuring the equivalence of the items of the translated questionnaire with descriptors of the original and translated instrument. 8,18 This equivalence, however, is not only due to the direct and literal translation of the questionnaire, but also the necessary adjustment of each question of the instrument, to ensure that each measurement objective is preserved in a new culture. 8,18 During the process of converting the PMI questionnaire to a Brazilian Portuguese version, it was necessary to remove three items from the original questionnaire. The first question (Question 4) was excluded using principal component analysis. The other two items (Questions 17 and 19) were excluded because they did not   The results of the present study showed a high internal consistency (Cronbach's alpha > 0.90) for the Brazilian Portuguese PMI, indicating that the items of the instrument correlate with both the other items and the final score. This metric, therefore, shows an aspect related to reliability. 18,19 Reliability was considered excellent for the intra-and inter-rater assessments (> 0.75), indicating that a set of PMI questions can evaluate pregnancy mobility, with similar results when the same respondents are assessed on different occasions without undergoing any change in health. 10 Interestingly, the data showed that there was a reduction in the mean score (21. ing their initial perception of mobility, considering that the 3 rd administration of the questionnaire did not precede mobility and range of motion tests. Despite these findings, the Bland-Altman agreement analysis revealed that there were no systematic and/ or random errors in the PMI scores attributed to true changes in mobility, as seen in Figures 1A-B Data analysis revealed a high prevalence of lower back pain during pregnancy, and it is widely known that pain and discomfort have a significant impact on the daily, domestic, and work activities of pregnant women. 21,22 Moreover, health education during pregnancy is an important tool to avoid inadequate movements in daily activities, and can be useful to prevent complaints about increased levels of pain. 24 The PMI proved to be a tool that could help health professionals identify inadequate movements, considering that the instrument individually points out the difficulty of movement execution. In a prospective cohort study, 23 223 pregnant women in the Netherlands were followed from the 12 th to 36 th week of gestation, and the results supported the use of PMI to evaluate physical factors that can help in the prevention of significant pain.
One limitation of the present study is the high educational